Abu 'Uthman al-Nahdi عبد الرحمن بن مل - أبو عثمان النهدي · The Book of the Sunnah

"The Messenger of Allah (ﷺ) said: 'Knowledge is based on three things, and anything beyond that is superfluous: a clear Verse, an established Sunnah, or the rulings by which the inheritance is divided fairly.'"